Rent-Seeking in Noxious Weed Regulations: Evidence from US States
Many non-native insect, disease, and weed pests of food, fiber, and nursery crops pose threats to
the U.S. environment, agricultural production, and exports. Prominent examples are citrus
canker and the Mediterranean fruit fly and, more recently, soybean rust (Animal and Plant Health
Inspection Service, APHIS, and Economic Research Service, ERS, US Department of
Agriculture, USDA). Among such threats, weed intrusions, commonly referred to as noxious
weeds, have significant environmental and economic impacts (Pimentel et al., 2000). Unwanted
weeds can be transmitted, knowingly or unknowingly, from one country or state to another
through both natural and human channels.
Noxious weeds are considered to be invasive species (IS), that is, “nonnative, alien, or
exotic to the ecosystem under consideration, and when introduced, cause, or are likely to cause,
economic or environmental harm or harm to human health,” (ERS, USDA, 2003). The Plant
Protection Act (PPA) prohibits or regulates the spread of such invasive species by authorizing
the Secretary of Agriculture to publish a federal list of noxious weeds (NXW) and to prohibit or
restrict their international and interstate commerce. Simultaneously, provisions of the Federal
Seed Act (FSA) prohibit or restrict noxious weed seed (NXWS) movements within and at the
borders of the United States. More importantly, the PPA and FSA allow each state’s Department
of Agriculture to maintain additional controls on noxious weeds deemed necessary to the state’s
ecological, agricultural and environmental interests. Hence, the definition of noxious weeds
varies by state, and most states maintain two sets of noxious weed regulations. Based on FSA,
the state-level NXWS list regulates interstate trade in seeds using a prohibited (zero tolerance)
and/or restricted (defined tolerance) list. The state-level NXW list is often based on the authority
granted by the PPA but, individual states also have noxious weed laws. The NXW list, which